#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
class equation{
private:
int a, b, c;
public:
equation(){}
equation(int aa, int bb, int cc):a(aa), b(bb), c(cc){}
~equation(){}
void solve();
};
void equation::solve()
{
if (a == 0) {...